Update ISSUE_TEMPLATE.md
Update ISSUE_TEMPLATE.md

Added example plunker, thanks to @nikmartin in #433 here is a demo plunker you can use as a starting point
https://plnkr.co/edit/C9mM5feGGZ0N7povA84G?p=preview
Textalk/angular-schema-form,json-schema-form/angular-schema-form,Textalk/angular-schema-form,json-schema-form/angular-schema-form